Add tests for file config map provider (#4575)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

config/configmapprovider/file_test.go

@@ -0,0 +1,59 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package configmapprovider
+
+import (
+	"context"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"go.opentelemetry.io/collector/config"
+)
+
+func TestFile_EmptyName(t *testing.T) {
+	exp := NewFile("")
+	_, err := exp.Retrieve(context.Background(), nil)
+	require.Error(t, err)
+}
+
+func TestFile_NonExistent(t *testing.T) {
+	env := NewFile(path.Join("testdata", "non-existent.yaml"))
+	_, err := env.Retrieve(context.Background(), nil)
+	assert.Error(t, err)
+}
+
+func TestFile_InvalidYaml(t *testing.T) {
+	env := NewFile(path.Join("testdata", "invalid-yaml.yaml"))
+	_, err := env.Retrieve(context.Background(), nil)
+	assert.Error(t, err)
+}
+
+func TestFile(t *testing.T) {
+	env := NewFile(path.Join("testdata", "default-config.yaml"))
+	ret, err := env.Retrieve(context.Background(), nil)
+	assert.NoError(t, err)
+	cfg, err := ret.Get(context.Background())
+	assert.NoError(t, err)
+	expectedMap := config.NewMapFromStringMap(map[string]interface{}{
+		"processors::batch":         nil,
+		"exporters::otlp::endpoint": "localhost:4317",
+	})
+	assert.Equal(t, expectedMap, cfg)
+	assert.NoError(t, ret.Close(context.Background()))
+	assert.NoError(t, env.Shutdown(context.Background()))
+}